She and classmates were amazed when a boy called Xie Yu Fei wrote to say he had found it. The 13-year-old was playing with friends when he found the balloon in the street.

The ticket attached to the string said he could win a prize if he wrote a letter to the school, so he put pen to paper.

Xieyufei, who says his English name is Nathan, said in the letter: "I'm in China, so I think it has travelled the farthest."

However, he lives too far away to claim the prize - a trip to Chester Zoo - so the pupils are sending him a box packed with letters, drawings and other goodies.

Headteacher Jason Redmond said: "You could have heard a pin drop when I showed the children on a map how far the balloon had flown.

Teaching

"It was one of those moments in teaching when it's such a pleasure to be at the front of the class telling the story."

Sue Wood, secretary of the Parent Teacher Association and organiser of the balloon race, said: "Until we received the letter, the farthest distance we had was Aintree. Some of the others were found near Irlam or Cadishead.

"I can't imagine how that balloon managed to get all the way to China. It must have got caught in the wing of a plane."

A spokesman for the Met Office said: "We've heard of balloons being found in Europe, but never this far before."

Guinness World Records said it does not monitor balloon races because there is little way of tracking the balloons for their entire journey.